This invention relates to an agitating type washing machine in which an agitating wheel is driven to operate reciprocally in opposite directions by a drive motor.
In an agitating type washing machine, an agitating wheel disposed in the center on a bottom of the machine is reciprocally rotated within a predetermined angle to effect intended washing operations, as widely known in the art. Conventionally, in order to effect such a reciprocal motion, such an agitating type washing machine includes a gearing, a link mechanism, and so on, by way of which rotation of a motor is transmitted to an agitating wheel. Thus, an agitating type washing machine is applicable particularly to a large volume washing machine. However, since a mechanism for producing a reciprocal motion therein is complicated and is thus expensive in cost, it is difficult to employ such a mechanism for a small washing machine.
In recent years, in order to introduce an agitating type into a small washing machine, an agitating type washing machine has been proposed in which a motor is directly controlled to run in opposite directions using a timer and so on to reciprocally rotate an agitating wheel. This system only necessitates control of duration of energization of a motor and thus can be produced advantageously at a low cost. However, it is disadvantageous in that reciprocal angular rotations of an agitating wheel will not be held constant depending upon variations in an amount of the washing, a voltage of a power supply, and so on, thus preventing sufficient performance of functions inherent to the agitating type.
In particular, since this system is a timing controlling system which utilizes a timer, an interval of time from interruption of energization of a motor to actual stopping thereof is long when the machine is run either without a load, that is, without any washing, or with a little washing. On the contrary, when the machine has a large amount of washing to wash, such washing acts to brake the motor and hence the motor is stopped in a reduced interval of time. Accordingly, if an interval of time required to stop a motor of the machine is determined for no load running of the machine which provides a maximum interval of time for stopping, then when there is a large amount of washing, some wasteful time will appear before the machine is run in the opposite direction after deenergization of the motor, resulting in deterioration in efficiency of washing. Further, since durations of energization of a motor are held constant, angular rotation of an agitating wheel will be large when there is a little washing, but on the contrary, when the machine has a large amount of washing, angular rotation of the agitating wheel will be small. Thus, the system is disadvantageous in that it presents characteristics which are reverse to those required for such a washing machine. Accordingly, if it is intended, in such conditions, to wash a given amount of washing, then when there is no water in a washing tank, that is, upon no load running of the machine, the agitating wheel may rotate in several rotations and thus there may possibly be a danger of a hand of a man or the like being caught by the agitating wheel. A system has also been proposed in which a plurality of water flows are determined in prior in accordance of amounts of washing and one of such water flows may be selected by means of a push button switch or the like each time the machine is used, in order to prevent damage. But, in this system, the amount of washing must be measured accurately each time the machine is used. Furthermore, such measurement is troublesome and results in insufficient attainment of performance of the washing machine. Besides, it is also disadvantageous in that, if an operator inadvertently forgot to selectively set a water flow, the clothing might be damaged.
A further system has also been proposed in which a number of controlled time intervals are provided in accordance with amounts of washing and are changed over to wash a given amount of washing. But, this system is also disadvantageous in that it is accompanied by a complicated control.